The present invention relates to an apparatus for heating plastics material pre-forms. In the field of the beverage production industry it has become customary to use plastics material containers for filling purposes. In this case plastics material pre-forms are usually shaped by blow moulding machines, and in particular stretch blow moulding machines, to form the plastics material containers. In these shaping processes, it is necessary for the plastics material pre-forms first to be heated. For this purpose, use is usually made in the prior art of infrared furnaces through which the plastics material pre-forms are conveyed. In this case, the plastics material pre-forms are conveyed past a series of heating modules.
In recent years, however, there has also been a move towards the provision of individual heating devices or heating cavities respectively, by means of which the individual plastics material pre-forms are heated. These heating cavities are usually arranged in this case on a common carrier. A procedure which has become known from the prior art in the heating of plastics material pre-forms consists in microwave furnaces. In this case, the individual operating stations of a microwave resonator are used to heat the PET plastics material pre-forms to a defined temperature profile. For the process control, on the one hand the temperature of the plastics material pre-forms in the heating zone is controlled for example by means of pyrometers and a rate of the method and also a switch-off point are adapted therewith. On the other hand, the resonator is also kept at its output maximum. In order to achieve this, the individual operating stations are frequently provided with pyrometers, plasma sensors, and also regulating devices such as for example tuning pins, and in addition, however, also with further measuring instruments.
In the prior art, the individual operating stations are controlled by a central control device such as a central PLC and are usually wired directly with the latter. The process control of an operating station is carried out substantially independently of other operating stations and also usually independently of the carrier, for example a rotor. In this case, however, the problem arises that the wiring is very expensive, since a considerable amount of sensor devices and actuating devices is required and these individual elements have to be actuated in each case. A correspondingly large amount of wiring also has to be detached and wired up again for replacement. A replacement of individual operating stations in the plant is therefore expensive. In addition, the operating stations can also not be pre-fabricated in series as a mechatronic unit, which results in a relatively low flexibility. In addition, the computing power and the wiring also have to be adapted with each change in the number of the operating stations.